Author
Topic: how the heck can i open my jar of jam? (Read 10239 times)

paul.fr

ever had one of those jars that just will not open? Or you take one from a girl to show how strong you are, then look a fool when you still can not budge the lid?In such cases, quite often ,a few taps on the bootom of the jar against a work surface will loosen the lid, why should that be?

The easiest way is to wind sticky tape around the outer rim of the lid to give a better grip or in the case of a jar where a partial vacuum results in pressure on the lid to simply punch a hole in it (spare lids should be stockpiled)

Turn the jar over and have a look underneath. There should be a two or more notches/indents on the rim of the lid that 'lock' the lid on. Just unlatch the notches with a little tweak of a knife, spoon or whatever you have lying around. Unscrew lid. Easy.

I don't think you'll find that the vacuum/low pressure inside many jars is a significant contributer to the difficulty of opening lids.I have enough strength to turn the lids, but find it's not always possible to grip the lid sufficiently (tightly?) to avoid slippage. This can be a particular problem if the lid (or hand) is wet or greasy (or, I suppose, if you had extra dry skin). If you can wipe (degrease by wiping with a cloth wetted with detergent-water) the lid and dry it (and hands) thoroughly, I find it helps a lot.Other than that, banging the bottom of the jar against a hard surface while trying to unscrew sounds promising.Part-used jars of honey with gummed-up threads are a different matter(!)

Turn the jar over and have a look underneath. There should be a two or more notches/indents on the rim of the lid that 'lock' the lid on. Just unlatch the notches with a little tweak of a knife, spoon or whatever you have lying around. Unscrew lid. Easy.

One should be very careful using metal tools to prise of lids, if you get tiny glass splinter's in your fingers they can cause pain and annoyance for weeks

lyner

I don't think you'll find that the vacuum/low pressure inside many jars is a significant contributer to the difficulty of opening lids.

Au contraire, I would say that the pressure on the whole lid can cause a force of, say 20N against the rim. If the coefficient of (static) friction is , say, 0.2, then you have an extra tangential force of 100N to overcome. that's like lifting 10kg.My figures are a bit ball-park but not ridiculous. Compare opening a new jar of jam- when it goes psssst, with opening it the next time. Isn't that all due to the changing pressure difference?

The most recalcitrant lids can be removed by the following technique.Use a pair of scissors to punch two small holes in the lid, partially open the scissors and insert each of the blades in each of the holes.Insert a bar between the blades close to the lid (a wooden spoon does fine).Get an assistant to hold the jar and rotate the lid taking advantage of the enhanced leverage provided by the bar.It is as well to use borrowed scissors and wooden spoon for this purpose

If you set the jar on the counter and give the cap a good thump with the palm of your hand, right in the middle of the jar lid, it breaks the vacuum and allows the jar to then open up upon untwisting again.

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